ShellPkg: Fixes for shell application launch, argument handling, and version output:

ShellPkg: Fixes for shell application launch, argument handling, and version output:
- Fixes shell application launch version output to match ‘ver’ command, as specified by the UEFI Shell spec.
- Adds PcdShellSupplier for <shell-supplier-specific-data> line of version output.  Defaulted to “EDK II”.
- Display only 1 startup.nsh countdown line per second instead of 10 per second.
- Fix issue where command line is just 1 or more “ “ characters and displayed garbage.
- Fix for @echo –off and @echo –on to not restore echo state

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chris Phillips <chrisp@hp.com>
reviewed-by: Jaben Carsey <Jaben.Carsey@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14784 6f19259b-4bc3-4df7-8a09-765794883524